The present invention relates to an irrigation valve adapted to be placed in an inlet pipe for irrigation liquid under a cultivation table for potted plants or the like, with the valve also comprising a means for draining liquid from the table and a means for aerating the liquid.
Valves of this type are used for the control of the introduction as well as the draining of irrigation water and/or nutrient fluid, which in the following will be referred to as irrigation liquid, in connection with cultivation tables on which are placed potted plants, cultivation blocks with plants and the like. At suitable intervals irrigation liquid is led to the table for irrigating the pots at the bottom, after which the liquid is drained for outlet or reuse. This type of irrigation is called ebb-and-flow-irrigation.
In, for example, Danish patent no. 146,812, irrigation valves are arranged in such a manner that the introduction and the draining is carried out through the same pipe, as the valve comprises movable parts providing for the necessary change-over. One of the drawbacks hereby is that the movable parts of the valve may fail, especially because the drained liquid often contains impurities such as algae, plant parts, residues of growth medium, etc. Besides, such valves are complicated and comprise several individual parts.
It is moreover a great advantage if the irrigation liquid is aerated before it is led to the cultivation table, as this increases the growth and results in healthier and stronger plants. Ordinary air, oxygen or CO.sub.2 may be used for the aeration depending on the product to be grown on the table. Means are known for the aeration of the irrigation liquid, but these means usually require application of air or gas under pressure and application of atomizer nozzles or the like. Hereby a complicated construction is achieved which requires regular maintenance, cleaning, adjustment, etc.